Hard disk drives have evolved to very small, yet essentially standardized packages, known in the art as "footprint" or "form factor". Essentially, a hard disk drive form factor is a three dimensional space which the drive occupies within an operating environment. Frequently, but not always, the hard disk drive form factor follows dimensions of a space or "well" set aside within a computer case or housing for holding a floppy disk drive, and it is a common practice to have hard disk drives follow the exterior envelope dimensions of floppy disk drives. Hard disk drive form factors which have become de facto standards include the 8-inch form factor, 51/4 inch full height form factor, 51/4 inch half height (1.6 inch) form factor, 31/2 inch full height (1.6 inch) form factor, 31/2 reduced height (one inch or less) form factor, 21/2 inch form factor, 1.8 inch form factor, and even a 1.3 inch form factor.
One dimension that tends to vary is the height dimension (as contrasted with the length and width dimensions). The height dimension or drive thickness is sometimes minimized, and hard disk drives which have reduced heights are known in the art. In some applications reduced-height hard disk drives are desired for a particular application, and a number of prior examples are available to establish the state of the art.
A number of factors have limited the amount of height reduction which has been realized in previous hard disk drive designs. Among these factors are disk-to-disk spacing with multiple disk drives, head gimbal assembly sizes and relative heights, actuator structures, etc., within the electromechanical portion of the hard disk drive known as "head/disk assembly". The other major subsystem of the hard disk drive is the electronics circuit board which has conventionally been secured to the head/disk assembly along one of the major walls of the drive unit, either adjacent to the base, or adjacent to the cover. The electronics circuit board has been a significant height limiting factor. While advances in miniaturization and large scale integration of electronics functions have aided reducing the size of drive electronics circuit boards, those size reductions have not, alone, been sufficient to overcome the conventional drawbacks with printed circuit board placement in the completed drives. Where a reduced height has become a design goal in the disk drive architecture, a number of approaches have been proposed involving rearrangement of the drive electronics circuit boards.
In commonly assigned U.S. Pat. No. 4,639,863 to Harrison et al., entitled: "Modular Unitary Disk File Subsystem", the drive electronics circuit board was arranged in an end-to-end alignment with the head/disk assembly so that the module could fit within an electronics expansion slot of e.g. a personal computer, rather than into the conventional floppy disk drive bay. Further, a small electronic integrated circuit board for driving a disk spindle motor was located in a well in the base of the head/disk assembly. While this approach worked well, it's result was to extend the length dimension of the assembled module.
In U.S. Pat. No. 5,025,336 to Morehouse et al., entitled: "Disk Drive Apparatus", overall height was reduced by reducing the height of the disk spindle motor assembly and rotary voice coil actuator, and by carefully placing electronic integrated circuits on a circuit board to occupy recesses formed in the drive base as contoured to accommodate the electromechanical components. This prior patent describes two flex circuits 92 and 94, shown in FIGS. 1 and 3, which carry head signals and motor driving currents between the printed circuit board and the actuator and spindle motor.
Another prior approach is illustrated by U.S. Pat. No. 5,235,482 to Schmitz, entitled: "Magnetic Disk Drive Incorporating a Mechanically Damped Base". In the approach of this patent, certain rectangular openings were defined in the sheet metal base of a size adapted to receive integrated circuit packages therethrough without shorting them out. A double-faced adhesively coated gasket, also having the same openings was then sandwiched between the base, and a printed circuit board carrying the drive electronics including the integrated circuit packages which protruded through the openings in the gasket and the base. Of note in this prior patent is a flex circuit in FIG. 13 which is described as carrying head signals and actuator coil currents from a connector end 1314 to delivery ends 1320 and 1326 on the actuator arm.
A further prior approach is described in U.S. Pat. No. 5,414,574 to Boutaghou et al., entitled: "Hybrid Base for Ultrathin Disk Drives". This patent describes a hybrid base plate and circuit board comprising a printed circuit board carrying the drive electronics and also including centrally a rigid metal insert for supporting the spindle motor and rotary actuator in relative alignment. The practice of using the drive base as the printed circuit board was also followed in the Victor Company of Japan, Limited, JVC J-D3812R and 3824R series of disk drives announced in 1986. In those drives, the base comprised a laminar printed circuit construction formed on top of a metal substrate.
One more example of a height reduced hard disk drive is described in European Patent Office Publication No. 0 534 745, entitled: "High Capacity, Low Profile Disk Drive System". This prior design features a circuit board in line with the storage disks and which slides into grooves 11c in a cover. The circuit board includes a connector which mates with another connector of a flex circuit leading to components in the enclosed space of the drive including voice coil actuator, heads preamplifier, spindle motor, etc. Another example of drive electronics circuit boards which are in line with the storage disks is provided in U.S. Pat. No. 5,038,239 to Vettel et al., entitled: "Integrated Electronic Card-Frame Assembly for a Rigid Disk Drive".
In another example known in the art, described for example in commonly assigned, pending U.S. patent application Ser. No. 08/490,962 by Viskochil, entitled: "Motor with Overmold Coil Support", filed on Jun. 15, 1995, an array of elastomeric conductors was employed to provide electrical connections between a drive electronics circuit board and a spindle motor of a hard disk drive. In an alternative arrangement described in that patent application metal pins extended from the spindle motor stator and through the base in order to enter a socket on the printed circuit board which in that example was mounted outwardly adjacent to the drive base wall.
While these various prior approaches represent design improvements enabling reduction in height dimension, they typically employ connectors between the circuit board or boards and flex circuits leading to electrical elements within the head/disk assembly and do not lend themselves to electrical contact connections. Also, the designs are not simple, and do not lend themselves to simplified drive assembly along a single assembly direction with the aid of robotics.